Sample code for uploading files directly with vanilla Javascript (XHR/CORS). Try the live version and drag & drop files to upload them to Google Drive.
If you'd like to use the code in your own project, copy upload.js and include it.
<script src="/path/to/upload.js"></script>
When uploading a file, create a new MediaUploader initialized with a Blob or
File and access token. Then call upload() to start the upload process.
var uploader = new MediaUploader({
file: content,
token: accessToken,
});
uploader.upload();
Your access token need to be authorized for any of the Drive scopes that permit writes (drive, drive.file, or drive.appdata.) You can go through one of the OAuth 2.0 flows to retrieve one or use Google+ Sign-In button.
See upload.js for additional parameters you can include when initializing the
uploader, including callbacks for success & failure events.